The present invention relates to a safety switch.
In a variety of environments, including for example industrial environments, there is a need for systems that are capable of preventing access to one or more pieces of equipment or machinery whilst that equipment or machinery is operating, in a manner that is highly reliable. In some circumstances, this may be achieved by the use of a safety switch.
Electrically operated machinery, for example, may be located within an enclosure. The enclosure may be a room, a cage, a specific area etc. When a person enters the enclosure, for example by opening a gate, the safety switch disconnects, grounds or otherwise isolates the electrical machinery from one or more power sources in a predictable, reliable manner. Thus, when a user enters the enclosure the chances of him/her suffering injury from the machinery are reduced or eliminated. In some circumstances, the machinery is not able to be restarted until the user has left the enclosure and reset the safety switch. While this is a useful safety feature, it is not very flexible.
In some circumstances it is conceivable that the user, while inside the enclosure, may still require the machinery to be operating in, for example a special mode (e.g. low speed or incremental movement mode), or, at the very least have control over its operation. For example, the user may wish to have electrical power maintained to the machinery within the enclosure so that he may test the equipment or clean the equipment. If the equipment within the enclosure is of a robotic nature, the user may wish to maintain power to the equipment so that he may teach the robot what to do. In this case, the robot must have some power to learn.
With prior art safety switches and enclosures, power is in general not supplied to the equipment while a user is in the enclosure. However, safety switches are known which do allow the supply of electrical power to machinery when in the enclosure. The safety switch is connected to the machinery and operable from within the enclosure. An example of such a safety switch has a handle moveable to three positions. In the first position, where no pressure is applied to the handle, the switch does not conduct electricity and no power is supplied to the machinery. When a certain amount of pressure is applied to the handle, electrical contacts within the switch are closed and the switch conducts electricity so that power is supplied to the machinery. If the handle is depressed further, for example due to the user reacting to a dangerous situation, the supply of electrical power to the machinery is cut-off and is not restored until the handle is moved to the second position.
Thus, it is an object of the present invention to provide a novel safety switch.